1. Field of the Invention
The invention relates to programming a communication device with identifying information.
2. Description of the Prior Art
Before a communication device, such as a radio telephone bought off-the-shelf, is fully functional it is necessary for the purchaser to sign up with a service provider. Although a telephone is manufactured with a unique Electronic Serial Number ESN, in order to connect to a radio telephone system of the purchasers choice (e.g. AWS or Bell Mobility), the radio telephone must be provided with sufficient information to identify the radio telephone user and the system to which it is connected for calls to be routed to it. This information is provided in the Number Assignment Module (NAM) information.
The NAM information includes a Mobile Identification Number (MIN) and data indicating the service provider chosen. In addition to this information relating to the specific radio telephone and service provider, the NAM includes security data used during registration to confirm the identity of the radio telephone and data providing details of a ‘Home Traffic Area’ and ‘System Control Channels’. The details of the ‘System Control Channels’ may include information relating to the level of service requested such as an access overload class providing information relating to the relative priority given to calls made by the specific subscriber. The radio telephone uses all this NAM information along with its ESN to gain access to the chosen radio telephone system.
With the increasingly wide use made of radio telephones, the need has arisen for their purchase at outlets other than the traditional dedicated shops. Phones are available for purchase at convenience stores and gas stations. Traditionally, the cost of a handset has been subsidized when the purchaser signs a contract for a period with a particular service provider. Without this subsidy, the cost of a handset is unattractive to the purchaser and in order to encourage customers to buy phones through nondedicated outlets, it is important that there is the potential for the handsets to be available with a subsidy.
A problem arises when the phones are not sold by dedicated sales outlets as it falls on the purchaser to secure a service provider and program the relevant NAM information into the phone. As under these circumstances the programmer is inevitably inexperienced, the procedure needs to be simple but also the service provider subsidizing the cost of the phone needs to be fairly certain that the purchaser is going to take out a contract with them rather than with a rival provider.
It will generally be, the purchaser who programs the phone under the above circumstances. Therefore, the process must be straightforward as the programmer will inevitably be relatively inexperienced.
The NAM is important to the functioning of the phone and the information stored in the NAM must therefore be well protected from inadvertent changes. To prevent the NAM from being changed inadvertently the storage of information at the relevant locations is code protected. It is therefore necessary for the purchaser to know the code in order to be able to program the NAM. This is where a problem arises. If the code is known to the purchaser, the NAM can be programmed with any data including data relating to a system provider other than the provider that subsidized the cost of the phone.
To prevent the customer from being free to choose any service provider when a subsidized phone has been purchased, the code has generally been made specific to a particular phone and retained by the service provider. This is because if a universal code were to be used this would soon be public knowledge and purchasers of subsidized phones would no longer need to sign up with a contract to the subsidizing provider. This would almost inevitably lead to the end of subsidized phones through nondedicated outlets.